Quartar-pel artifacting

[Zarxrax]

I've done a few tests now with the Quarter-pel option enabled, and with it disabled. The tests with it enabled look terrible! It leaves behind traces of dirt behind motion. On top of that, it tends to increase filesizes a bit! Is anyone else experiencing the same thing with this setting? I'm wondering what the purpose of the setting actually is!

[BluDChyLD]

i just encoded a movie using q-pel, doesn't seem to be any probs yet. It supposed to reduced macroblocks, apparently it works better at 1/4 res.
BluDChyLD

[Difflam]

I'm getting the same thing Zarxrax, in fact, all the advanced "features" of DivX5.0 pro are giving me undesirable results
:(

[BluDChyLD]

just encoded leon with DivX 5 Pro, skipping through the movie i don't see and visible problems. Used q-pel again... Do these artifacts go through the whole movie?

[Doom9]

I did some qpel tests too.. and as a result changed the guide to say don't use it. maybe it looks good on a shitty playback device (TV) but on the pc it creates some sort of moving texture over considerable parts of the image.. and that's very irritating to my eyes. b frames and gmc worked pretty well though but I'm still not through testing.

[quickstang45]

I did an encoding last night using qpel. It did some terrible things to the movie. Looked terrible! I will not be using it anymore. Also using qpel it really slowed my encoding time down. I am using doom9's guide on divx 5 with vdub. With the job control it doesnt show the fps its encoding at. Wish I knew.

[Doom9]

while it's encoding, go to the main virtualdub window.. there's only one menu, click on it and select the first option and it will show you the statistics

[Mystion]

I have encoded three entire movies using DivX5 Pro, only the whose output verical and horizontal resolution were divisible by 16 did not give any kind of artifacts whatsoever with all three (Q-Pel, GMC and B Frames) advanced options activated... Nonethelless I got a slightly (around 80MB...) larger file than what expected, but the results of that last encoding have been excellent... So I must verify as well the divisible by 16 rule, however it may be just casual, more testing is needed...

[Minako]

supposed to mean qpel only artifacts on non mod16 resolutions???

[Vanos_b]

80 MB "slightly"? Were you aiming for a 100 GB file?
Done some tests myself (640x352 Wild Wild West using AviSynth/VirtualDub): QPEL produces blocks instead of removing them, PSY (strong) produces some random color blocks, but QPEL+PSY -> a real mess. Filesize is acurate withing 0.6% (~4 MB), so not very but acceptable. I'll go for GMC/B-frames and no QPEL/PSY/PREPROC for now, and the results are quiet ecouraging.

[hofmetzger]

im glad im not the only one...
i encoded on my brothers pc, the result was great, but when looking on my own pc it was terrible: blocks movin around, even scenes with no action at all where "destroying" themselves into vertical lines until the next keyframe. the point is that it looks great on the pc's of my two brothers, and terrible on mine.

my pc: win2000 sp2 on amd k6-2 450 with v3 3000

my brothers pc's:
win2000 no sp, athlon 1300 with geforce 2

win98se athlon 1000 with v3 3500

[Minako]

you been watching the very same movie? One time with artifacts, one time not??? Must be some system-dependent problem in the ds-filter??? Strange.

[hofmetzger]

yes im very sure its the same movie :)
i've even tried several craphic drivers but it dont changes anything. i'll try to make screenshots...

btw: im encoding for a while (since 3.12-times), thats the 1st time i noticed sth like that, so its not a wrong thing with my pc.

[Minako]

Keep us informed :-)

[hofmetzger]

here u can see a part of an frame on mine and on one of my brother's pc.
its not one of the worst parts, but i think u can see a big difference.

http://www.schlachtbank.de/vergleich.jpg

my encoding details (copied out of divX config-dialog)

-b22 660 -r 640,288,4 -key 200 -log "c:\divx.log" -mv "c:\mvinfo.bin" -p -b -g -q -dr 12,4,2000,10,20 -sc 50 -pq 5

btw i cant play it without small hangings, even dvd runs better (on my slow k6-2). im wondering if the sysrequirements have increased so much form divx4.x to 5

[Minako]

the nearest conclusion would be qpel ds-decoding is kinda buggy creating artifacts on some systems...

Or do the same problems occur when decoding with vfw, too?

[hofmetzger]

switched hardware acc in the options of wmp to null, didnt help, so i dont belive its my graphicscard.

ds/vfw: how to switch to / use vfw instead of ds?

[BluDChyLD]

my guess is that DivX 5 is more demanding on your pc. Hence the good playback on your brothers faster machine...

[Minako]

easiest way to playback with vfw (should be slower) is to regsvr32 /u divxdec.ax (register again with regsvr32 divxdec.ax)

or simply take the shots from Video loaden into vdub, that also decodes with vfw.

[hofmetzger]

but IMHO cpu speed doesnt influence the visual quality.
(at least not in virtual dub, where my screenshots are taken from). so it might be sth with win2000 sp2 and/or my k6-2.
(i think of wrong optimizations or so, _not cpu-speed_)

@all with same/similar problems: what are your systems?

[hofmetzger]

@chibi jasmin: well, even in VDub it looks terrible(scrshots).
so what about the others here? same problems in VDub?

[Minako]

Same problem in VDub? One system good, the other not?

This is odd...then there must be a bug in the ds-filter and in the vfw-decoder!?!??! No clue...

[dragoman]

Odd....I have encoded about 5 movies with DivX 5.0 Pro with qpel enabled....no problems at all with visual quality.

dragoman

[hofmetzger]

this is exactly the point. i dont belive all having problems with qpel did sth wrong. as i can see there are many with no problems at all.
if the pc your are running is the reason, who can say if it looks as good as now, when you change sth in your configuration or buy a new one (bad english i know :-)

at the moment i make the same movie without qpel, if there are still these terrible artifacts for me, i have to excuse -- if not, i think we have to keep qpel deactivated until there is a fix or new version of divx.

the best was, if someone know how to change configuration so this isnt any longer a problem :confused:

[BluDChyLD]

using b-frames and q-pel im getting the following artifacts, notice the white specs on the image?

Image 1 - The specs are usually this big, and blink on and off in different places. They appear every 20-30secs.

http://homepage.ntlworld.com/dawson.thomas/artifact1.bmp

Image 2 - These specs behave in the same way, but are alot bigger. This is the only one i've noticed so far, but shows how big they can get.

http://homepage.ntlworld.com/dawson.thomas/artifact2.bmp

Is anyone else getting similar artifacts? Im guessing it's the q-pel thats doing it. I'll re-encode the film tonight without the extra settings and see what results I get.
BluDChyLD

[simon79]

I've encoded the lobby scene in Matrix, to test my settings. First I got these terrible artefacts, the picture was green and blocky. I've encoded without qpel, but the other 2 options activated. The problem depends not on qpel, because I've activiated it to test it. So I did the clip in an other Resolution (old was 608*240) new: 640*256, and no artifacts at all.
I don't know why because 608 is divisable by 16(32) too. I know the screenshot is not very representative, but I think you can see it. When I loaded the bad videoclip in Vdub and played it there, it looked normal.
Any Ideas what the Problem is, and how to solve it (Dshow filters ?)

PS: the picture often looks same for 1 sec when switching from FullScreen to windowed, with every DivX5 video.

[Markstar]

Got the same problem as hofmetzger - it looks perfect on one computer (Athlon 600, Win2k SP2) and on the other where I encoded it (TB 850, Win98 & Win2k) I have the dirt you guys where talking about and also the edges weren't perfect at all.
Had qp, gmc & be activated, but it was 16x8 (640x264). Weired thing is, after installing DivX 5, I have the same problem on older (3.11, 4.12) movies as well - they look perfect on the one and crappy on the other computer.
Any ideas? :confused:

Edit: Well, found out that in my case the problem was the desktop color depth (yeah, I know it's stupid). When I used DivX 5 I had to have at least 24Bit (as stated in the min. req, btw) - then all movies looked perfect (3.11, 4.12 & 5), otherwise I'd have the noise.
Uninstalling DivX 5 and then reinstalling 4.12 still gave me the noise with 16Bit, but installing Win from scrap and only 4.12 worked for all movies with 16Bit (except the 5, of course).

Somebody knows why DivX 5 needs the 24Bit to play the movies (even the ones that looked great with 16Bit before)???